1. Field of the Invention
This invention relates to a double seal nut having a first seal located within an internal bore to engage a threaded bolt and prevent leakage of fluid in an axial direction along the bolt and a second seal carried on the load bearing surface of the nut to prevent leakage in a radial direction along the interface between the load bearing surface and a workpiece upon which the load bearing surface is seated.
2. Background Art
Threaded seal nuts have long been used in industry, particularly the aerospace industry, to be mated to a correspondingly threaded bolt to hold together two typically planer and adjacent metal workpieces through which the bolt extends. It is common for a seal ring that is manufactured from a self-lubricating material (e.g. commercially known as Teflon) to be retained within a snap-in groove formed in a longitudinally extending bore through the interior of the nut. When the bolt is received within the bore of the nut, the seal ring is deformed around the threads of the bolt to prevent the leakage of fluid in a longitudinal (i.e. axial) direction along the bolt.
However, the conventional seal ring located at the interior bore of a seal nut has no effect on blocking the leakage of fluid in a radial direction along the interface between the nut and an opposing workpiece. By way of example, such liquid may be moisture originating from jet fuel carried by an aircraft. Leakage has been known to occur when an excessive torque is applied to tighten the seal nut on the bolt or as a consequence of vibrations to which the seal nut is subjected when the aircraft is in flight.
The typical solution for blocking such leakage of fluid in the radial direction is to use a sealant around the nut. In some cases, the sealant build-up is as much as 1/8 to 1/4 inches thick. Not only is the process of applying the sealant expensive and time consuming, but the addition of the sealant undesirably contributes to the overall weight of the aircraft. With the large number of seal nuts used to build modern aircraft, the weight increase introduced by the volume of sealant can often be significant.
Therefore, it would be desirable for a seal nut to have the ability to prevent the leakage of fluid in both the axial direction through the internal bore of the nut and the radial direction along the bearing surface without using a sealant.